"fold": a replacement for "reduce"

[monarch_dodra]

On Tuesday, 25 March 2014 at 21:16:22 UTC, Nordlöw wrote:
>> You have no guarantees that you'll have "stability" of the 
>> returned type.
>
> What do you mean with "stability" of the return type?
>
>> More often than not, it *is* stable, but there are cases where 
>> it is not.
>
> Could you gives examples of when it's stable and when it's not?

Actually, not with a trivial use case.

I think I'm over-engineering.